Inducible Clindamycin Resistance in Staphylococcus aureus isolated from pus samples in an Orthopaedic tertiary care centre.

Introduction: Clindamycin is a commonly used antibiotic to treat skin and soft tissue infectionscaused by Staphylococcus aureus particularly Methicillin-Resistant Staphylococcus aureus (MRSA)infection. In vitro routine tests for clindamycin susceptibility may fail to detect inducible clindamycinresistance due to genes resulting in treatment failure, thus necessitating the need to detect suchresistance by a simple D - test on a routine basis. Materials and Methods: 165 isolates ofStaphylococcus aureus were subjected to routine antibiotic susceptibility testing including Oxacillin(1μg) and Cefoxitin (30μg) by Kirby Bauer disc diffusion method. Inducible clindamycin resistancewas detected by D test as per CLSI guidelines on erythromycin resistant isolates. Results: 24(14.5%) isolates showed inducible clindamycin resistance, 8 (4.84%) showed constitutive resistancewhile the remaining 59 (35.75%) showed MS phenotype. Inducible clindamycin resistance and MSphenotype were found higher in MRSA (21.42%, 40.47%) as compared to MSSA (7.40%, 30.86%).Conclusion: This study showed that the D test should be used as a mandatory method in routinedisc diffusion testing to detect inducible clindamycin resistance.